Phosphorothioate modification improves exon-skipping of antisense oligonucleotides based on sulfonyl phosphoramidates in mdx mouse myotubes.

2'-O-Methyl (2'-OMe) antisense oligonucleotides (AOs) possessing a various number of 4-(trimethylammonio)butylsulfonyl or tosyl phosphoramidates (N+ and Ts-modifications, respectively) instead of a native phosphodiester linkage were designed to skip exon-23 in dystrophin pre-mRNA transcript in mdx mice myotubes. AOs bearing several zwitterionic N+ modifications in the sequence had remarkably increased thermal stability towards complementary mRNA in comparison with 2'-OMe-RNAs having negatively charged Ts and phosphorothioate (PS) linkages. However, only Ts-modified AOs exhibited a similar level of exon skipping in comparison with fully modified PS-containing 2'-OMe-RNA, whereas the exon skipping induced by N+ modified AOs was much lower with no exon-skipping detected for AOs having seven N+ modifications. The level of exon-skipping was improved once Ts and especially N+ moieties were used in combination with PS-modification, most likely through improved cellular and nuclear uptake of AOs. These results provide new insights on expanding the design of novel chemically modified AOs based on phosphate modifications.

Evaluation of Phosphorus and Non-Phosphorus Neutral Oligonucleotide Backbones for Enhancing Therapeutic Index of Gapmer Antisense Oligonucleotides.

The phosphorothioate (PS) linkage in an essential component of therapeutic oligonucleotides. PS in the DNA region of gapmer antisense oligonucleotides (ASOs) supports RNaseH1 activity and enhances nuclease stability. PS also promotes binding to plasma, cell surface, and intracellular proteins, which facilitates tissue distribution, cellular uptake, and endosomal escape of PS ASOs. We recently showed that site-specific replacement of PS in the DNA gap with methoxylpropyl phosphonate (MOP) linkages can enhance the therapeutic index of gapmer ASOs. In this article, we explored 18 phosphorus- and non-phosphorus-based neutral backbone modifications to determine the structure-activity relationship of neutral linkages for enhancing therapeutic index. Replacing MOP with other alkyl phosphonate and phosphotriester linkages enhanced therapeutic index, but these linkages were susceptible to chemical degradation during oligonucleotide deprotection from solid supports following synthesis. Replacing MOP with non-phosphorus linkages resulted in improved chemical stability, but these linkages were introduced into ASOs as nucleotide dimers, which limits their versatility. Overall, linkages such as isopropyl and isobutyl phosphonates and O-isopropyl and O-tetrahydrofuranosyl phosphotriesters, formacetal, and C3-amide showed improved activity in mice relative to MOP. Our data suggest that site-specific incorporation of any neutral backbone linkage can improve therapeutic index, but the size, hydrophobicity, and RNA-binding affinity of the linkage influence ASO activity.

Defense Mechanism of Phosphorothioated DNA under Peroxynitrite-Mediated Oxidative Stress.

DNA phosphorothioation (PT) exists in many pathogenic bacteria; however, the mechanism of PT-DNA resistance to the immune response is unclear. In this work, we meticulously investigated the peroxynitrite (PN) tolerance using PT-bioengineered E. coli strains. The in vivo experiment confirms that the S+ strain survives better than the S- strain under moderately oxidative stress. The LCMS, IC, and GCMS experiments demonstrated that phosphorothioate partially converted to phosphate, and the byproduct included sulfate and elemental sulfur. When O,O-diethyl thiophosphate ester (DETP) was used, the reaction rate k1 was determined to be 4.3 ± 0.5 M-1 s-1 in the first-order for both phosphorothioate and peroxynitrite at 35 °C and pH of 8.0. The IC50 values of phosphorothioate dinucleotides are dramatically increased by 400-700-fold compared to DETP. The SH/OH Yin-Yang mechanism rationalizes the in situ DNA self-defense against PN-mediated oxidative stress at the extra bioenergetic cost of DNA modification.

Development of an ICP-MS/MS approach for absolute quantification and determination of phosphodiester to phosphorothioate ratio in therapeutic oligonucleotides.

A new analytical method based on ICP-MS/MS is proposed for the characterization of synthetic phosphorothioate oligonucleotides. Absolute quantification of oligonucleotides is challenging, as well as the determination of phosphodiester to phosphorothioate ratio for phosphorothioate oligonucleotides. Both are considered as critical quality attributes and should be determined using robust validated methods. The method we developed was designed to be easy to apply, fast, and robust. It allows simultaneous absolute quantification of an oligonucleotide (based on the quantification of phosphorus), determination of the phosphodiester to phosphorothioate ratio (based on the quantification of phosphorus and sulfur) and optionally determination of sodium (or any other metal) as a counter ion. The performance of the method was demonstrated on O,O-diethyl thiophosphate potassium salt, a well characterized model substance that possesses similar composition to phosphorothioate oligonucleotides. Method was also tested on different synthetic phophorothioate oligonucleotides, showing excellent accuracy and precision.

Targeting Endothelial Ligands: ICAM-1/alicaforsen, MAdCAM-1.

Specific blockade of the endothelial ligands intercellular adhesion molecule-1 [ICAM-1] and mucosal addressin cell adhesion molecule [MAdCAM] involved in leukocyte recruitment to the site of inflammation as therapeutic targets in inflammatory bowel disease [IBD] has been recognized from their overexpression in the inflamed mucosa and successful intervention based on these ligands in preclinical animal models. Interventions to target ICAM-1 in human IBD are confined to the ICAM-1 anti-sense oligonucleotide alicaforsen. While results with parenteral formulations of alicaforsen in Crohn's disease have largely been negative, efficacy signals derived from studies with an enema formulation in ulcerative colitis and pouchitis are promising and have led to a Food and Drug Administration Fast-Track designation for the latter. A large phase III programme in pouchitis is underway. Phase II studies with the anti-MAdCAM-1 antibody [SHP647] delivered positive results in ulcerative colitis and anti-inflammatory signals in Crohn's disease. Furthermore, it was shown that SHP647 does not affect the number and composition of cells in cerebrospinal fluid, suggesting that the compound is not affecting immune surveillance in the central nervous system. In addition, both alicaforsen and SHP647 are promising compounds based on the clear safety profile observed so far.

Alicaforsen, an Antisense Inhibitor of Intercellular Adhesion Molecule-1, in the Treatment for Left-Sided Ulcerative Colitis and Ulcerative Proctitis.

BACKGROUND: Data on the efficacy of intercellular adhesion molecule-1 antisense oligonucleotide alicaforsen in ulcerative colitis (UC) is inconsistent. METHODS: All patients, who had received at least one dose of alicaforsen, were analyzed retrospectively. Alicaforsen's efficacy was assessed in patients treated for left-sided UC and proctitis by comparing clinical and (if applicable) endoscopic disease activity before/after treatment. RESULTS: Twelve patients were treated for left-sided UC or proctitis. Eleven patients received a 6-week course of a once-daily 240 mg alicaforsen enema formulation. In 1 patient, treatment was discontinued, because it was found to be inefficient. Disease activity measured by the partial Mayo score and 6-point symptom score was significantly reduced after treatment (6.0 vs. 2.4, p = 0.011 and 3.7 vs. 1.4, p = 0.008). Faecal calprotectin showed a trend towards reduction (484.4 vs. 179.5 µg/g, p = 0.063). Clinical improvement was achieved in 10 patients (83.3%). In 7 patients, a relapse occurred (70%). Median duration of clinical improvement was 18.0 weeks (range 1-112). Three patients showed an ongoing improvement of >9 months. No adverse events were reported. CONCLUSIONS: A 6-week course of alicaforsen seemed to be safe and efficacious in inducing clinical improvement in patients with left-sided UC and proctitis. Prolonged clinical improvement was observed in many but not all patients.

Alicaforsen for the treatment of inflammatory bowel disease.

INTRODUCTION: Intracellular adhesion molecule-1 (ICAM-1), is a transmembrane glycoprotein of the immunoglobulin family, constitutively expressed on vascular endothelial cells and upregulated in inflamed colonic tissue. Alicaforsen, a 20 base ICAM-1 anti-sense oligonucleotide and highly selective ICAM-1 inhibitor, down-regulates ICAM-1 mRNA. Areas covered: We review mechanism of action, pharmacokinetics, pre-clinical, clinical and safety data of alicaforsen for the treatment of ulcerative colitis (UC), pouchitis and Crohn's disease (CD). Expert opinion: After 6 weeks of treatment, topical alicaforsen was significantly more effective than placebo in inducing remission in patients with moderate-severe distal UC, with treatment effects lasting up to 30 weeks. No difference was observed in head-head comparison with mesalamine topical enema, although alicaforsen appeared to have more durable treatment effect. Clinical trials of an intravenous formulation in Crohn's disease showed no significant treatment effect compared to placebo. An open-label trial in alicaforsen for pouchitis demonstrated encouraging results, now being assessed in a multi-national phase 3 trial. No major safety signals have been observed in UC patients treated with alicaforsen enemas. The potential as a novel therapy for pouchitis has led to orphan designation for this indication by the FDA and European Medicines Agency.

Antisense approach to inflammatory bowel disease: prospects and challenges.

Despite the great success of anti-tumour necrosis factor-based therapies, the treatment of Crohn's disease (CD) and ulcerative colitis (UC) still remains a challenge for clinicians, as these drugs are not effective in all patients, their efficacy may wane with time, and their use can increase the risk of adverse events and be associated with the development of new immune-mediated diseases. Therefore, new therapeutic targets are currently being investigated both in pre-clinical studies and in clinical trials. Among the technologies used to build new therapeutic compounds, the antisense oligonucleotide (ASO) approach is slowly gaining space in the field of inflammatory bowel diseases (IBDs), and three ASOs have been investigated in clinical trials. Systemic administration of alicaforsen targeting intercellular adhesion molecule-1, a protein involved in the recruitment of leukocytes to inflamed intestine, was not effective in CD, even though the same compound was of benefit when given as an enema to UC patients. DIMS0150, targeting nuclear factor (NF) κB-p65, a transcription factor that promotes pro-inflammatory responses, was very promising in pre-clinical studies and is currently being tested in clinical trials. Oral mongersen, targeting Smad7, an intracellular protein that inhibits transforming growth factor (TGF)-ß1 activity, was safe and well tolerated by CD patients, and the results of a phase II clinical trial showed the efficacy of the drug in inducing clinical remission in patients with active disease. In this leading article, we review the rationale and the clinical data available regarding these three agents, and we discuss the challenge of using ASOs in IBD.

New approach to the determination phosphorothioate oligonucleotides by ultra high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry.

This text presents a novel method for the separation and detection of phosphorothioate oligonucleotides with the use of ion pair ultra high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry The research showed that hexafluoroisopropanol/triethylamine based mobile phases may be successfully used when liquid chromatography is coupled with such elemental detection. However, the concentration of both HFIP and TEA influences the final result. The lower concentration of HFIP, the lower the background in ICP-MS and the greater the sensitivity. The method applied for the analysis of serum samples was based on high resolution inductively coupled plasma mass spectrometry. Utilization of this method allows determination of fifty times lower quantity of phosphorothioate oligonucleotides than in the case of quadrupole mass analyzer. Monitoring of (31)P may be used to quantify these compounds at the level of 80 µg L(-1), while simultaneous determination of sulfur is very useful for qualitative analysis. Moreover, the results presented in this paper demonstrate the practical applicability of coupling LC with ICP-MS in determining phosphorothioate oligonucleotides and their metabolites in serum within 7 min with a very good sensitivity. The method was linear in the concentration range between 0.2 and 3 mg L(-1). The limit of detection was in the range of 0.07 and 0.13 mg L(-1). Accuracy varied with concentration, but was in the range of 3%.

Phosphorothioate oligonucleotides: effectiveness and toxicity.

BACKGROUND: Many experimental and clinical studies have focused on the antisense strategy. In this context phosphorothioate oligonucleotides are compounds addressed to hybridize to a targeted mRNA inducing a variety of effects including inhibition of the expression of proteins involved in different pathological processes and preventing translation. METHODS: In this review, we provide an update on clinical efficacy and toxicological profile of phosphorothioate oligonucleotides used in experimental and clinical studies, also focusing on the use of the antisense strategy in the context of Duchenne muscular dystrophy which is a key pathology to study different aspects of this therapy. Pubmed/Medline was searched using the keyword "Phosphorotioate" combined with "Antisense", "Oligonucleotide" and "Duchenne muscular dystrophy". CONCLUSIONS: Phosphorothioate oligonucleotide transient activation of the complement cascade represents the most evident toxicological response, as showed by in vivo studies. It is also known that many of these compounds induce a prolongation of activated partial thromboplastin time, a reaction which is often highly transient and proportional to the oligonucleotide plasma concentrations, making that effect clinically insignificant for the current treatment regimens. In summary, current evidence shows limited untoward effects and reversibility of the damage induced, at least for some of those compounds, with promising effectiveness for treatment of various pathologies.

Meta-analysis using individual patient data: efficacy and durability of topical alicaforsen for the treatment of active ulcerative colitis.

BACKGROUND: The antisense ICAM-1 inhibitor alicaforsen has been studied in four phase 2 studies in ulcerative colitis (UC). Recruited patients varied as to the extent of their colitis and in the severity of disease at entry. AIM: To investigate the efficacy of alicaforsen enema in specific UC populations. Efficacy was analysed for short-term (week 6-10) and long-term (week 30) outcomes compared with either placebo or a high-dose mesalazine (mesalamine) enema in patients with disease extent up to 40 cm from the anal verge in patients with moderate or severe disease, and in patients with both of these features. METHODS: Individual patient data meta-analyses of 200 patients from four phase 2 studies evaluating nightly alicaforsen 240 mg enema and comparators. Patient data were pooled and analysed in a single data set. Continuous outcomes were evaluated using anova; dichotomous outcomes were evaluated using Pearson chi-square or Fisher's exact tests. RESULTS: Alicaforsen showed superior efficacy vs. placebo in: patients with disease extent up to 40 cm, patients with moderate and severe disease and especially when both those conditions were satisfied. In these patient groups, mesalazine also showed short-term efficacy. At week 30, however, the efficacy of mesalazine waned and alicaforsen became significantly more efficacious. CONCLUSIONS: This post hoc meta-analysis showed that alicaforsen is effective in patients with active UC, especially in patients with distal disease, which is of moderate/severe activity. The efficacy of alicaforsen was durable in these sub-groups, suggesting a disease-modifying effect. This analysis suggests that alicaforsen enema may offer an effective, potentially durable response in moderate/severe distal active UC.

Preclinical evaluation of the toxicological effects of a novel constrained ethyl modified antisense compound targeting signal transducer and activator of transcription 3 in mice and cynomolgus monkeys.

ISIS 481464 is a constrained ethyl (cEt) modified phosphorothioate antisense oligonucleotide (ASO) targeting signal transducer and activator of transcription 3 (STAT3) studied in mice and monkey to support oncology clinical trials. Six-week toxicology studies were performed in mice and cynomolgus monkey (up to 70 and 30 mg/kg/week respectively). Reduction in STAT3 protein up to 90% of control was observed in monkey. Cynomolgus monkey was considered the most relevant species to human with respect to pharmacokinetic properties, but mice are useful in their relative sensitivity to the potential proinflammatory and hepatic effects of oligonucleotides. In monkeys, there was no impact on organ function at doses up to 30 mg/kg/week for 6 weeks. Minimal to slight proximal tubular epithelial cell degeneration and regeneration within the kidney was observed, which had no impact on renal function and showed reversibility at the end of the treatment-free period. Additionally, mild and transient activated partial thromboplastin time elevations and mild increases in complement Bb were observed at the higher doses by intravenous dosing only. In mice, the alterations at 70 mg/kg/week included spleen weight increase up to 1.4-fold relative to control, increases in alanine aminotransferase and aspartate aminotransferase up to 1.8-fold over control, interleukin-10 increases up to 3.7-fold, and monocyte chemoattractant protein-1 increase up to 1.9-fold over control. No significant clinical pathology or histopathology changes were seen in mice at 20 mg/kg/week or less. The toxicity profile of ISIS 481464 is consistent with effects observed with phosphorothioate ASOs containing 2'-O-methoxyethylribose modifications instead of cEt.

Targeted Therapy in Inflammatory Bowel Disease; Current Status and Future Perspectives / 한양의대학술지

Novel biologic agents that selectively target specific molecules and pathways have been developed recently for the management of inflammatory bowel disease (IBD). Anti-TNF-alpha, an antibody to TNF-alpha is one of the first newly developed drugs to dramatically improve the symptoms of patients with IBD. Therapy with anti-TNF-alpha demonstrates a new paradigm for management of IBD and early treatment with these drugs has demonstrated increased benefit. However, more than one-third of the patients have lost response to the drug. Also, there is the problem of antibody formation. Therefore, enormous efforts to develop novel drugs as an alternatives to anti-TNF-alpha are underway. Anti CD4+ T cell cytokine including IL-12/23 and IL-17 blockers, selective anti-adhesion molecules known as natalizumab, vedolizumab and alicaforsen, T-cell proliferation inhibitors, anti-inflammatory cytokines, immune stimulators, growth factors and mitogen activated protein kinase (MAPK) inhibitors are among the novel therapeutic agents that are currently being investigated for efficacy and safety in the management of IBD. The aim of this paper is to review current knowledge concerning the mechanism of action, the short and long term efficacy, and the safety of these novel biologic therapies, as well as that of anti-TNF-alpha, in IBD.

Selective covalent conjugation of phosphorothioate DNA oligonucleotides with streptavidin.

Protein-DNA conjugates have found numerous applications in the field of diagnostics and nanobiotechnology, however, their intrinsic susceptibility to DNA degradation by nucleases represents a major obstacle for many applications. We here report the selective covalent conjugation of the protein streptavidin (STV) with phosphorothioate oligonucleotides (psDNA) containing a terminal alkylthiolgroup as the chemically addressable linking unit, using a heterobifunctional NHS-/maleimide crosslinker. The psDNA-STV conjugates were synthesized in about 10% isolated yields. We demonstrate that the terminal alkylthiol group selectively reacts with the maleimide while the backbone sulfur atoms are not engaged in chemical conjugation. The novel psDNA-STV conjugates retain their binding capabilities for both biotinylated macromolecules and the complementary nucleic acid. Moreover, the psDNA-STV conjugate retained its binding capacity for complementary oligomers even after a nuclease digestion step, which effectively degrades deoxyribonucleotide oligomers and thus the binding capability of regular DNA-STV conjugates. The psDNA-STV therefore hold particular promise for applications e.g. in proteome research and novel biosensing devices, where interfering endogenous nucleic acids need to be removed from analytes by nuclease digestion.

Thiolated polycarbophil as an adjuvant for permeation enhancement in nasal delivery of antisense oligonucleotides.

The purpose of this study was to investigate the effect of thiolated polycarbophil as an adjuvant to enhance the permeation and improve the stability of a phosphorothioate antisense oligonucleotide (PTO-ODN) on the nasal mucosa. Polycarbophil-cysteine (PCP-Cys) was synthesized by the covalent attachment of L-cysteine to the polymeric backbone. Cytotoxicity tests were examined on human nasal epithelial cells from surgery of nasal polyps confirmed by histological studies. Deoxyribonuclease I activity in respiratory region of the porcine nasal cavity was analyzed by an enzymatic assay. The enzymatic degradation of PTO-ODNs on freshly excised porcine nasal mucosa was analyzed and protection of PCP-cysteine toward DNase I degradation was evaluated. Permeation studies were performed in Ussing-type diffusion chambers. PCP-Cys/GSH did not arise a remarkable mortal effect. Porcine respiratory mucosa was shown to possess nuclease activity corresponding to 0.69 Kunitz units/mL. PTO-ODNs were degraded by incubation with nasal mucosa. In the presence of 0.45% thiolated polycarbophil and 0.5% glutathione (GSH), this degradation process could be lowered. In the presence of thiolated polycarbophil and GSH the uptake of PTO-ODNs from the nasal mucosa was 1.7-fold improved. According to these results thiolated polycarbophil/GSH might be a promising excipient for nasal administration of PTO-ODNs.

Therapeutic silencing of microRNA-122 in primates with chronic hepatitis C virus infection.

The liver-expressed microRNA-122 (miR-122) is essential for hepatitis C virus (HCV) RNA accumulation in cultured liver cells, but its potential as a target for antiviral intervention has not been assessed. We found that treatment of chronically infected chimpanzees with a locked nucleic acid (LNA)-modified oligonucleotide (SPC3649) complementary to miR-122 leads to long-lasting suppression of HCV viremia, with no evidence of viral resistance or side effects in the treated animals. Furthermore, transcriptome and histological analyses of liver biopsies demonstrated derepression of target mRNAs with miR-122 seed sites, down-regulation of interferon-regulated genes, and improvement of HCV-induced liver pathology. The prolonged virological response to SPC3649 treatment without HCV rebound holds promise of a new antiviral therapy with a high barrier to resistance.

Advantageous toxicity profile of inhaled antisense oligonucleotides following chronic dosing in non-human primates.

TPI ASM8 and TPI 1100 are two products containing modified phosphorothioate antisense oligonucleotides (AONs), which are undergoing development for the treatment of asthma and chronic obstructive pulmonary disease (COPD), respectively. TPI ASM8 is comprised of two AONs, one targeting the human chemokine receptor 3 (CCR3) and the other targeting the common beta-chain of the IL-3/IL-5/GM-CSF receptors. TPI 1100 is also a dual-AON compound targeting the phosphodiesterase (PDE) 4 and 7 isotypes. For both products, the AONs are present in a 1:1 ratio by weight. Both products will be administered by inhalation to patients, and TPI ASM8 is currently undergoing Phase 2 clinical trials. As part of the safety assessment of both products, the toxicity and disposition (i.e., pharmacokinetics of the AON components in plasma and tissues) were investigated in 14-day inhalation studies in monkeys at doses ranging from 0.05 to 2.5mg/kg/day. Results indicated that both products were safe and well tolerated at all dose levels. Reversible treatment-related alterations were only observed at the high dose levels tested and were limited to changes in the respiratory tract which were characterized primarily by the presence of alveolar macrophages in the absence of a generalized inflammatory response. Plasma pharmacokinetic profiles showed very low plasma concentrations, and no plasma accumulation was observed after repeated doses. While significant amounts of the AONs of both TPI ASM8 and TPI 1100 were measured in trachea and lung, only limited amounts of the AONs could be measured in kidney and liver, which, in combination with the low plasma level data, is indicative of very low systemic exposure. Taken together, these results demonstrate that these two new AON-based products are safe and that delivery via the inhaled route achieves localized deposition in the pulmonary tract with very limited systemic exposure and reduced toxicity compared to other routes of AON administration.

Amb a 1-immunostimulatory oligodeoxynucleotide conjugate immunotherapy increases CD4+CD25+ T cells in the nasal mucosa of subjects with allergic rhinitis.

BACKGROUND: We have previously shown that short-course treatment with Amb a 1-immunostimulatory phosphorothioate oligonucleotide conjugate (AIC) before the ragweed season modifies the response of the nasal mucosa to allergen challenge in ragweed-sensitive patients by increasing Th1 cytokines and decreasing both Th2 cytokines and eosinophilia after the ragweed season. The effect of AIC immunotherapy on CD4+CD25+ T cell expression in the nasal mucosa is unknown. OBJECTIVE: To determine the in vivo effect of short-course AIC immunotherapy on CD4+CD25+ regulatory T cells in the nasal mucosa of ragweed-sensitive subjects. METHODS: 19 ragweed-sensitive patients with allergic rhinitis were randomly assigned to receive either 6 escalating doses of AIC (0.06-12microg; n = 12) or placebo (n = 7) at weekly intervals immediately before the 2001 ragweed season. Nasal biopsies were taken at baseline prior to immunization and again post immunization 24 hours after ragweed allergen challenge at the start and end of the ragweed season. The expression of T regulatory cells, IL-10 and TGF-beta was assessed at each time point by immunohistochemistry. RESULTS: The numbers of allergen-induced CD4+-, CD4+CD25+-, IL-10- and TGF-beta-positive cells in the nasal mucosa after AIC immunization before the ragweed season did not differ between the two groups. Repeat challenge after the ragweed season led to a significant increase in CD4+CD25+ cells in AIC-compared with placebo-treated subjects. A trend toward an increase in IL-10-positive cells in the AIC-treated group did not reach statistical significance. CONCLUSIONS: Short-course AIC immunotherapy increases CD4+CD25+ regulatory T cell infiltration in the nasal mucosa following allergen challenge after seasonal ragweed-pollen exposure.

Safety of biologic therapy.

Several biologic agents have been assessed in patients with inflammatory bowel disease (IBD; Crohn's disease [CD] and ulcerative colitis [UC]). Until recently, only infliximab (humanized monoclonal anti-TNF-alpha antibody) had been approved by the Food and Drug Administration (FDA) to induce and maintain remission in patients with active mild to moderate and/or fistulizing Crohn's disease who are refractory to conventional therapy. Two recent trials, ACT 1 and ACT2, observed high efficacy of infliximab in inducing and maintaining clinical remission, mucosal healing, and corticosteroid-sparing effects in patients with moderate to severe UC. This agent also was recently approved by the FDA for the treatment of ulcerative colitis to reduce signs and symptoms, to induce clinical remission and healing of the intestinal mucosa, and to eliminate the use of corticosteroids in patients with moderately to severely active UC who have had an inadequate response to conventional therapy. There have been many randomized, double-blind, controlled and open-label uncontrolled studies of large and small numbers of patients assessing the efficacy and safety of various biologic agents considered potentially useful in the treatment of IBD. Among all the biologic agents, infliximab has the most robust data on safety. This is because it has been evaluated in many more trials than has any other biologic agent. In addition, postmarketing experience provides very valuable information about adverse events occurring during treatment with this agent.

Safety and efficacy of two dose formulations of alicaforsen enema compared with mesalazine enema for treatment of mild to moderate left-sided ulcerative colitis: a randomized, double-blind, active-controlled trial.

BACKGROUND: Alicaforsen is an antisense oligonucleotide inhibitor of intercellular adhesion molecule 1 protein expression with activity in subjects with ulcerative colitis and pouchitis. AIM: To compare the effects of alicaforsen enema to standard of care mesalazine (mesalamine) enema in subjects with mild to moderate active left-sided ulcerative colitis. METHOD: A randomized, double-blind, active-controlled multicentre clinical trial. Subjects received a nightly enema of 120 mg alicaforsen (n=55), 240 mg alicaforsen (n=50), or 4 g mesalazine (n=54) for 6 weeks, followed by a 24-week monitoring period. The primary end point was Disease Activity Index at week 6. Clinical improvement, remission and relapse were secondary end points. RESULTS: No significant difference was observed between treatment arms in the primary end point. However, the median duration of response to alicaforsen enema treatment was two- to threefold longer (128 and 146 days) in comparison with mesalazine (54 days). Complete mucosal healing occurred in 24% of the 240 mg alicaforsen group, when compared with 17% in the mesalazine. CONCLUSIONS: Alicaforsen enema demonstrated an acute response and safety profile similar to mesalazine enema, but was differentiated by a more durable response. The extended length of remission suggests that alicaforsen enema treatment may have a disease modifying effect.